1,2-Bis[5-(9-ethyl-9H-carbazol-3-yl)-2-methyl­thio­phen-3-yl]-3,3,4,4,5,5-hexa­fluoro­cyclo­pentene

Koji Kubono; Teruo Synmyouzu; Kenta Goto; Tsuyoshi Tsujioka; Keita Tani

doi:10.1107/S1600536811029539

. 2011 Jul 30;67(Pt 8):o2194. doi: 10.1107/S1600536811029539

1,2-Bis[5-(9-ethyl-9H-carbazol-3-yl)-2-methylthiophen-3-yl]-3,3,4,4,5,5-hexafluorocyclopentene

Koji Kubono ^a,^*, Teruo Synmyouzu ^b, Kenta Goto ^b, Tsuyoshi Tsujioka ^a, Keita Tani ^a

PMCID: PMC3213625 PMID: 22091202

Abstract

The title compound, C₄₃H₃₂F₆N₂S₂, is a new symmetrical photochromic diarylethene derivative with 9-ethylcarbazol-3-yl substituents. The molecule adopts a photoactive antiparallel conformation [Irie (2000). Chem. Rev. 100, 1685–1716; Kobatake et al. (2002). Chem. Commun. pp. 2804–2805], with a dihedral angle between the mean planes of the two thiophene rings of 56.23 (6)°. The distance between the two reactive C atoms is 3.497 (3) Å. In the crystal, two molecules are associated through a pair of C—H⋯F intermolecular hydrogen bonds, forming a centrosymmetric dimer. Dimers are linked by weak π–π interactions [centroid–centroid distance = 3.8872 (13) Å], forming chains along the c axis.

Related literature

For a review of diarylethenes, see: Irie (2000 ▶). For related structures, see: Irie et al. (1995 ▶, 2001 ▶); Kobatake et al. (2002 ▶); Takami & Irie et al. (2004 ▶). For a review of carbazole, see: Grigalevicius (2006 ▶). For hydrogen-bond motifs, see: Bernstein et al. (1995 ▶).

Experimental

Crystal data

C₄₃H₃₂F₆N₂S₂
M _r = 754.85
Monoclinic,
a = 14.6687 (7) Å
b = 17.0977 (8) Å
c = 14.0017 (7) Å
β = 95.798 (3)°
V = 3493.7 (3) Å³
Z = 4
Cu Kα radiation
μ = 1.97 mm⁻¹
T = 123 K
0.34 × 0.18 × 0.11 mm

Data collection

Rigaku R-AXIS RAPID diffractometer
Absorption correction: multi-scan (ABSCOR; Higashi, 1995 ▶) T _min = 0.687, T _max = 0.806
40777 measured reflections
6393 independent reflections
5482 reflections with F ² > 2σ(F ²)
R _int = 0.045

Refinement

R[F ² > 2σ(F ²)] = 0.049
wR(F ²) = 0.139
S = 1.00
6393 reflections
479 parameters
H-atom parameters constrained
Δρ_max = 0.90 e Å⁻³
Δρ_min = −0.50 e Å⁻³

Data collection: PROCESS-AUTO (Rigaku, 2006 ▶); cell refinement: PROCESS-AUTO; data reduction: CrystalStructure (Rigaku/MSC, 2006 ▶); program(s) used to solve structure: SIR92 (Altomare et al., 1993 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: PLATON (Spek, 2009 ▶); software used to prepare material for publication: CrystalStructure.

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536811029539/bv2188sup1.cif

e-67-o2194-sup1.cif^{(32.4KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811029539/bv2188Isup2.hkl

e-67-o2194-Isup2.hkl^{(308.3KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811029539/bv2188Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C26—H26⋯F2ⁱ	0.95	2.44	3.290 (2)	149 (1)

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Symmetry code: (i) Inline graphic .

Acknowledgments

This work was supported by a Grant-in-Aid for Science Research on Priority Area "New Frontiers in Photochromism (No. 471)" and Science Research(C) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan, and was performed under the Cooperative Research Program of "Network Joint Research Center for Materials and Devices".

supplementary crystallographic information

Comment

Diarylethenes are well known photochromic compounds both in solution and in solid state (Irie, 2000), and have attracted much attention because of their potential application to optical memory, photoswitches (Irie, et al. 2001), and display devices (Takami & Irie, 2004). It was reported that diarylethenes can undergo a photochemical ring-closure reaction in the crystalline phase when the ring-opening forms are in the anti-parallel conformation and where the distance between two reactive C atoms is shorter than 4.2 Å (Irie, et al. 1995; Kobatake, et al. 2002). Therefore, X-ray analysis of diarylethenes will give valuable information for their photochromism in solid state. We have prepared the title compound, (I), a symmetrical diarylethene derivative containing carbazole moiety as hole transport material (Grigalevicius, 2006) to study not only its photochromism but also its electrical properties. In this paper, the molecular and crystal structure of (I) is presented.

In the molecular structure of (I), the thiophene rings are located in a photoactive anti-parallel conformation which can effectively undergo photocyclization reactions; with the dihedral angle between the mean planes of two thiophene rings, S1/C6–C9 and S2/C26–C28, of 56.23 (6) ° (Fig. 1). The dihedral angles between the thiophene rings and adjacent carbazole moieties are 23.49 (5) ° for S1/C6–C9 and N1/C11–C22, and 23.19 (5) ° for S2/C26–C28 and N2/C30–C41. The distance between two reactive C atoms in ring-closure reaction, C7···C28, is 3.497 (3) Å. This distance is shorter than 4.2 Å, suggesting that (I) can undergo the ring-closure reaction and photochromism in the crystalline phase by UV irradiation.

In the crystal structure of (I), there are intermolecular C—H···F hydrogen bonds (Fig. 2 and Table 1). Two molecules are associated through a pair of C—H···F intermolecular hydrogen bonds, forming a centrosymmetric dimer with a R₂²(14) ring motif (Bernstein et al., 1995). In the crystal, intermolecular C···C distances between carbazole moieties for C30···C36ⁱⁱ and C34···C34ⁱⁱ [symmetry code: (ii) 1 - x, 2 - y, 2 - z] are 3.657 (3) and 3.659 (3) Å, respectively. Dimers are linked by weak π–π interactions between carbazole moieties to give one-dimensional supramolecular chains propagating along the c axis.

Experimental

The title compound, (I), was prepared by the treatment of 3-bromo-5-(9-ethylcarbazolyl)-2-methylthiophene with butyl lithium, then with octafluorocyclopentene. The product was recrystallized from benzene-hexane to give plate crystals, m.p. 458–460 K; ¹H NMR (CDCl₃, p.p.m. 400 MHz): 1.45 (t, J = 7.2 Hz, 6H, Et), 2.05 (s, 6H, CH₃), 4.38 (q, J = 7.2 Hz, 4H, Et), 7.20–7.24 (m, 2H, carbazole), 7.32 (s, 2H, thiophene). 7.39–7.43 (m, 2H, carbazole), 7.47–7.52 (m, 2H, carbazole), 7.67 (dd, J = 7.8 Hz, J' = 1.6 Hz, 2H, carbazole), 8.11 (d, J = 7.8 Hz, 2H, carbazole), 8.25 (d, J = 1.6 Hz, 2H, carbazole); HRMS(FAB): calculated for C₄₃H₃₂F₆N₂S₂: 754.1911, found(M⁺): 754.1908.